The present invention relates to magnetic bubble memory devices with associative processing capabilities and particularly to an arrangement wherein storage loop organizations provide reduced access time to data stored in the storage loops.
One of the concerns in the development of associative magnetic domain memories is the reduction in access time to data (bubbles and voids) stored in memory. A number of prior art devices attempting to impart associative capability to magnetic bubble domain memories utilizes the techniques of either interaction of bubble domains with current carrying conductors or interaction between two bubble domains to achieve the objective e.g. U.S. Pat. Nos. 3,761,886 and 3,760,390. Since these techniques require interaction with stored data itself, it is felt that the reliability has something to be desired. Moreover, the time required for association was long enough to be prohibitive. In a large association memory the access time for search of each block and time required for decision becomes very important. Further, a number of prior art devices have a magnetic domain memory utilizing a plurality of minor loops which are accessed through a major loop. When accessed to the stored data is desired, the bits comprising the data are transferred serially from the minor loops to the major loops and serially transferred to the sensor to be read.
Various other techniques are utilized for transferring data to and from one or more circulating minor storage loops all with a view towards reducing access time to the stored data. One prior art device shown in U.S. Pat. No. 3,971,005, though not an associative memory, utilizes a plurality of unconnected minor loops in which a writing circuit is located on one side of the loops and a read-out circuit is located on the other side of the loops to reduce access time necessary for the data bits to circulate completely around the loops before being accessed. It is also necessary in this technique to load the data back into the storage loops. Another technique disclosed in U.S. Pat. No. 3,838,407, though not an associative memory, is to use a bubble memory in which the read-in and read-out of data from a plurality of minor loops occurs at several locations in the loops thus reducing access time still further.
Nonetheless, a number of short comings, in addition to the above, have been observed in the prior art. First, the information once transferred from the minor loops to the major loop before transfer back into the minor loop. Further, the prior art devices required controllers to track the position of the circulating data in the minor loops since the location of the bubble in the minor loop with respect to its exit point to the major loop must be known to track the position of the data in the minor loops. Such controllers require current carrying conductors to perform such operations and these techniques were non-reliable and also required multiple sensor points.
It is, therefore, a primary object of this invention to provide a magnetic bubble memory device with associative processing capabilities and having an arrangement of storage loop organizations which provide reduced access time to the data stored in the storage loops and to utilize existing technology in such an arrangement, already found to be reliable. It is still another object to provide a bubble memory with associative processing capabilities utilizing the memory device itself to provide such capabilities.